1. Field of the Invention
The present invention relates to an LC composite component produced by forming input and output electrodes and an LC resonant circuit in a laminated body obtained by stacking a plurality of dielectric layers.
2. Description of the Related Art
LC composite components having a configuration in which an LC resonant circuit is formed in a laminated body obtained by stacking dielectric layers have been used. When an LC composite component serves as a high-frequency filter, a notch circuit is sometimes connected to an LC resonant circuit such that the resulting curve becomes steep at an attenuation pole (see, e.g., Japanese Unexamined Patent Application Publication No. 9-153704).
A known filter will now be described.
FIG. 1 is a circuit diagram of a filter in which notch circuits are connected to corresponding LC resonant circuits.
A coupling capacitance C5 is connected between an input terminal P1 and an output terminal P2. A first LC resonant circuit having an inductance L1 and a capacitance C1 connected in parallel is connected between the input terminal P1 and the ground terminal. A second LC resonant circuit having an inductance L2 and a capacitance C2 connected in parallel is connected between the output terminal P2 and the ground terminal. A mutual inductance M is formed between the inductance L1 and the inductance L2, so that the first and second LC resonant circuits are magnetically coupled to each other.
A notch circuit having an inductance L3 and a capacitance C3 connected in series is connected between the input terminal P1 and the ground terminal. A notch circuit having an inductance L4 and a capacitance C4 connected in series is connected between the output terminal P2 and the ground terminal.
The filter having the notch circuits therein is provided with electrodes that form the capacitances and inductances of the notch circuits, as well as electrodes that form the capacitances and inductances of the LC resonant circuits. This increases not only the circuit area by the size of the electrodes, but also the number of layers in the filter.